1. Field of the Invention
The present invention relates to a method of making anhydrous lithium thiocyanate and solutions containing anhydrous lithium thiocyanate. More particularly, the present invention is directed to the method of making the anhydrous lithium thiocyanate and the solutions containing that material by metathetical reaction techniques, as more fully developed below.
2. Description of the Prior Art
There have been many techniques developed over the past few years for the synthesis of inorganic-alkali metal and organic-alkali metal salts. For example, Kunze et al, J. Phys. Chem. 67, 385 (1963) describe the preparation of lithium tetraphenyl boride by the reaction of sodium tetraphenyl boride with lithium chloride in ethanol, and Bhattacharyya et al, J. Phys, Chem. 69, 608 (1965) describe the preparation of alkali metal tetraphenyl boride salts by the reaction of sodium tetraphenyl boride with lithium chloride in THF solvent. Revzin et al, Chemical Abstracts 70, 28974 q (1969) and Chemical Abstracts 71, 3416 s (1969) describe the preparation of lithium tetraphenyl boride from various salts, including ammonium tetraphenyl boride with lithium-containing ion exchange resins in acetone. Likewise, Kirgintsev et al, Chemical Abstracts 72, 139078 m (1970) describe the formation of lithium tetraphenyl borate and sodium tetraphenyl borate using potassium tetraphenyl borate with an ion exchange resin of the lithium form and using acetone solvent. Kozitskii, Chemical Abstracts 79, 83825 c (1973) describe the preparation of lithium tetraphenyl borate and the like by reaction of the potassium analogue with a lithium-containing ion exchange resin in the presence of acetone and water. (It should be noted that various prior art references refer to the same compounds as tetraphenyl borate or as tetraphenyl borides.) Kohl'kin et al, Chemical Abstracts 85, 86471 u (1976) describe the preparation of lithium tetraphenyl boride from sodium tetraphenyl boride but do not describe the source of lithium except to point out that it is an exchange synthesis, i.e. exchange extraction synthesis. Wittig et al, Ann. 563, 110 (1949) and Chemical Abstracts 46, 6607 d (1952) respectively teach the preparation of lithium tetraphenyl boride and the like from triphenyl boron and trifluoro boron sources reacted with lithium phenyl salt in ether solvents. Grassberger et al, Angew. Chem. Int. Ed. Engl. 8, 275 (1969) describe the preparation of various alkali metal tetraorganyl borates by reaction of, for example, triphenyl boron with lithium tetraethyl boride without solvent.
Lee, Oakridge National Laboratory contribution to the Journal of Inorganic Chemistry, Volume 3, No. 2, Feb. 1964, pp. 289-90 describes the synthesis of lithium thiocyanate from hydrated lithium hydroxide and ammonium thiocyanate. U.S. Pat. No. 3,049,406 describes the preparation of anhydrous lithium salts, including lithium halides, lithium pseudohalides, such as lithium cyanide and lithium thiocyanate, by the reaction of lithium hydride with halogens, cyanogen or thiocyanogen in an ether solution. The dehydration of hydrated thiocyanate salts to form anhydrous thiocyanates is also described by S. Petrucci (J. Phys. Chem. 82, pp. 545-552, 1978).
Notwithstanding all of the aforementioned prior art directed to various methods of preparing alkali metal salts, to date no reference has been published which teaches or renders obvious the methods of preparation described herein.